The Expanding Earth Model
The modern geologists have come up with a fascinating revelation that the seven continents were once one single super continent called Pangaea. Pangaea was located on one side and it was surrounded by one vast ocean. This single super continent then started breaking up in pieces and drifting away from each other. This explanation is known as the plate tectonic theory. The plate tectonic theory further explains that the tectonic plates that are underneath the land keeps continuously drift over ocean. This process result in a process called subduction where the ocean crusts are further pushed into the molten region which leads to the expansion of the sea bed through seafloor spreading process.
Another idea that tries to explain the expansion of the earth states that the earth was much smaller than it is today and over time it expanded. The justification to this idea is that if the continental regions are rearranged and put together, so that they form a large continent, they appear to fit together just like the jigsaw puzzle. Despite the distortion due to physical processes over time, the landmasses seem to fit well. A good example is that Africa continent seem to fit quite well with South America continent. If all the continents are drifted close together to the adjacent continent, they form a single uniform large landmass.
The main evidence of the earth expansion lies on the thickness of the crust. The thickness of the earth varies from thirty to fifty kilometers over the land and over the ocean areas, the thickness variation ranges from five to ten kilometers. Another significant thing to note is that the transition between the land areas and ocean areas is not smooth since the change in thickness happens abruptly and this happens exactly at the continental shelves. There are several explanations as to why the crust is not uniform. Scientists explain that water cannot sit on hot magma because it could turn the water to vapor. Another explanation is that crust at the ocean cooled faster because of losing heat thus making the ocean crust thicker.
Some scientists argue that the continents came about as a result of effects of the gravitational force. The magma that was in molten form was pulled up by the force of gravity into the sphere and it started cooling slowly. It took many years for the huge mass to loss heat and hardened into what was known as Pangaea. During the cooling process, the outer surface cooled faster than the interior causing some heat to be conserved in the interior. The interior temperature started to rise leading to the expansion of the crust which made the single huge mass called Pangaea to break into pieces and the huge pieces (the continent) floated on the ocean.
Lastly, it has been explained scientifically that the earth expanded due to pressure and the gravity. The force of gravity exerts a lot of pressure on the surface of the earth making it to expand. This makes the level of gravity force and density of the inner region to reduce significantly. This results in the reduced pressure around the core of the earth which then expands as a result making the earth to expand.